Person: KORTEN, VOLKAN
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KORTEN
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VOLKAN
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Publication Metadata only Susceptibility of bacterial isolates from Turkey - A report from the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program(TAYLOR & FRANCIS LTD, 2007) KORTEN, VOLKAN; Eraksoy, H.; Basustaoglu, A.; Korten, V.; Kurt, H.; Ozturk, R.; Ulusoy, S.; Yaman, A.; Yuce, A.; Zarakolu, P.The study monitored the susceptibility of nosocomial pathogens to meropenem and comparator antimicrobial agents isolated as part of the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program from Turkish university hospitals. In terms of minimum inhibitory concentration 90% (MIC90) values, meropenem was two- and eight-fold more active than imipenem against Escherichia coli and Klebsiella pneumoniae, respectively. 40.5% of K. pneumoniae, 23.1% of Klebsiella oxytoca and 15.3% of E. coli isolates were extended-spectrum P-lactamase (ESBL) producers. Piperacillin/tazobactam was the most active agent against isolates of Pseudomonas aeruginosa, followed by meropenem and imipenem. Against Acinetobacter baumannii isolates, meropenem and imipenem were the most active agents. Continued surveillance by the MYSTIC Program appears to be prudent to help focus on effective empiric treatment regimens.Publication Metadata only 11th European Congress on Clinical Microbiology and Infectious Diseases - Istanbul, Turkey, 2 April 2001 - Introduction(W B SAUNDERS CO LTD, 2002) KORTEN, VOLKAN; Finch, R; Korten, VPublication Metadata only Antibiotic resistance surveillance over a 4-year period (2000-2003) in Turkey: results of the MYSTIC Program(ELSEVIER SCIENCE INC, 2007) KORTEN, VOLKAN; Korten, Volkan; Ulusoy, Sercan; Zarakolu, Pinar; Mete, BirgulThe Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program is a global study that provides antimicrobial susceptibility data in centers prescribing meropenem. The activity of meropenem and 7 broad-spectrum antimicrobials have been examined against 5208 bacterial isolates from 9 Turkish centers between 2000 and 2003. Cumulative susceptibility rates against all species of Enterobacteriaceae combined were ranked as follows: meropenem (99.3%), imipenem (97.6%), cefepime (80.0%), piperacillin-tazobactam (73.6%), ceftazidime (70.3%), ciprofloxacin (70.1%), cefotaxime (66.9%), and tobramycin (67.2%). The production of extended-spectrum beta-lactamases (ESBLs) was detected in 48.7% of Klebsiella pneumoniae and in 19.5% of Escherichia coli isolates. Of ESBL producing K. pneumoniae isolates, 75.7% were resistant to tobramycin, 40.3% to ciprofloxacin, and 48.3% to piperacillin-tazobactam. Only piperacillin/ tazobactam and carbapenems were active against more than 50% of Pseudomonas aeruginosa at the National Committee for Clinical Laboratory Standards-susceptible breakpoint, and the carbapenems were the most active compounds against Acinetobacter spp. These data confirm the continued potency of meropenem against Enterobacteriaceae in units where it is actively being prescribed. (c) 2007 Elsevier Inc. All rights reserved.Publication Metadata only Influence of oral glycopeptides on the fecal flora of human volunteers: Selection of highly glycopeptide-resistant enterococci(Oxford University Press, 1996) KORTEN, VOLKAN; Van Der Auwera P., Pensart N., Korten V., Murray B.E., Leclercq R.Changes in fecal flora were evaluated in 22 healthy volunteers administered oral vancomycin or teicoplanin in 1989-1991 in Belgium. Evaluation of 5 colonies per subject revealed no glycopeptide-resistant enterococci in the predominant flora before glycopeptide administration; however, large numbers (mostly Enterococcus faecium) emerged by the end of the study in 14 (64%) of the subjects. Pediococci and lactobacilli also increased in number. In 1992, 40 healthy volunteers and 33 cancer patients were evaluated by plating stool samples directly onto selective media containing vancomyein; low numbers of vancomycin-resistant enterococci (<50 cfu/g) were found in 11 (28%) of the 40 and 4 (12%) of the 33 samples, respectively. DNA restriction fragment length polymorphism analysis showed that most isolates were different, but all contained vanA in Tn1546-like elements. These results indicate that vanA and Tn1546-like elements were common in Belgium as early as 1989 and that community-based individuals in that location likely form a major reservoir for glycopeptide-resistant enterococci.Publication Metadata only Subcutaneous nodules caused by Pseudomonas aeruginosa: healing without incision and drainage(1992) KORTEN, VOLKAN; Korten, V.; Gürbüz, O.; Firatli, T.; Bayik, M.; Akoglu, T.In a patient with multiple myeloma, numerous indurated, subcutaneous nodules and pyomyositis due to Pseudomonas aeruginosa were noted. These lesions resolved with ciprofloxacin plus ceftazidime therapy without surgical incision and drainage. Despite another course of cancer chemotherapy after total disappearance, there were no recurrences at the end of 3 months. Quinolones initially combined with other antipseudomonal beta-lactam agents may be the drugs of choice in the management of patients with subcutaneous nodules caused by P. aeruginosa.Publication Metadata only Impact of the Fluoroquinolones on Gastrointestinal Flora(1993) KORTEN, VOLKAN; Korten V., Murray B.E.A number of studies have been performed to evaluate the effect of the fluoroquinolones on gastrointestinal flora. The fluoroquinolones have only slight or no effect on the oropharyngeal flora, except when Neisseria, Haemophilus or Branhamella spp. are present. Studies have consistently shown that Gram-negative facultative bacteria of the lower intestinal flora are strongly suppressed during administration of these agents. Total faecal anaerobes are generally unchanged. The effect of the fluoroquinolones on Gram-positive bacteria is more variable with mild to moderate suppression reported with some agents. In view of the high faecal concentrations of the fluoroquinolones, the general lack of effect on anaerobes is surprising; it may be attributable to the large number of microorganisms found in faeces and faecal binding of the fluoroquinolones. Several recent studies suggest that the effects of some fluoroquinolones on faecal anaerobes and Gram-positive cocci may be more profound in certain patient populations such as bone marrow transplant recipients and patients undergoing gastrointestinal surgery. Colonisation with yeasts and the emergence of resistant bacterial strains have been reported during or after fluoroquinolone administration in some studies. Future studies will need to investigate the effect of the newer agents with greater activity against anaerobes and Gram-positive cocci on the gastrointestinal flora and to continue surveillance for resistant organisms. © 1993, ADIS International Limited. All rights reserved.Publication Metadata only Comparison of cefepime and ceftazidime in combination with amikacin in the empirical treatment of high-risk patients with febrile neutropenia: A prospective, randomized, multicenter study(TAYLOR & FRANCIS AS, 2001) KORTEN, VOLKAN; Erman, M; Akova, M; Akan, H; Korten, V; Ferhanoglu, B; Koksal, I; Cetinkaya, Y; Uzun, O; Unal, SA total of 208 adult patients with cancer and febrile neutropenia from 5 medical institutions were randomized to receive either cefepime (2 g b.i.d.) or ceftazidime (2 g t.i.d.) in combination with amikacin (15 mg/kg/o.d.). Ninety-seven patients in the ceftazidime (CEZ) group and 98 in the cefepime group (CEF) were evaluable for efficacy. In 68 patients (35%), infection could be documented. The average duration of antibiotic therapy was 11 and 12 d and response rates to the empirical regimen were 36 and 30% for the CEZ and CEF groups, respectively (p>0.05). The average time of defervescence in responders was 3 d for both groups. Modification of the initial regimen with antivirals and/or azole antifungals raised the number of responders to 44% and 35%, respectively (p>0.05). Vancomycin was additionally given to 29 patients in the CEZ group and to 27 patients in the CEF group. Twenty-six patients in each group received empirical amphotericin B. Mild, reversible study drug-related side-effects were observed in 12 patients (12%) in the CEZ group and 13 patients (13%) in the CEF group (p>0.05). Cefepime in combination with amikacin seems to be as effective, safe and tolerable as ceftazidime + amikacin in patients with high-risk neutropenia and fever.Publication Metadata only Antimicrobial prophylaxis in management of urinary tract stones by extracorporeal shock-wave lithotripsy: is it necessary?(1995) KORTEN, VOLKAN; Ilker, Y.; Türkeri, L. N.; Korten, V.; Tarcan, T.; Akdaş, A.OBJECTIVES: In a prospective randomized study, we evaluated the incidence of urinary tract infections following extracorporeal shock-wave lithotripsy (ESWL) and the necessity of prophylactic antibiotic administration in patients treated with this modality. METHODS: A total of 360 consecutive patients with renal and ureteric stones who had sterile urine before ESWL treatment and did not have any increased risk of infection received either a single dose of 400 mg of ofloxacin or no prophylaxis. Patients were followed by simple urine analysis and urine cultures together, with clinical evaluations. RESULTS: Only 3 patients (0.8%) had positive urine cultures at 1 week after ESWL. Two of these patients were in the antibiotic prophylaxis group. CONCLUSIONS: The incidence of urinary tract infections after ESWL is extremely low, provided that patients have sterile urine before ESWL, and prophylactic antibiotics are not required.Publication Metadata only Bactericidal activity of the fluoroquinolone DU-6859a alone and in combination with other antimicrobial agents against multiresistant enterococci(1996) KORTEN, VOLKAN; Korten, V.; Erdem, I.; Murray, B. E.The in vitro activity of DU-6859a (DU) alone and in combination with various antimicrobials was evaluated against multiresistant enterococci including some isolates with defined gyrA mutations. DU produced rapid in vitro killing against most enterococci that lacked resistance to ciprofloxacin, but it was not bactericidal against strains with MICs of ciprofloxacin of > or = 8 micrograms/ml, or against one of four strains with an MIC of ciprofloxacin of 4 micrograms/ml. The combination of DU with rifampin was antagonistic against two of two isolates tested. Combinations of DU and novobiocin, gentamicin, or a beta-lactam (amoxicillin, ampicillin-sulbactam, or amoxicillin-clavulanate) were generally indifferent. When different beta-lactams were used together, with or without DU, bactericidal activity was observed against some isolates. Despite the absence of synergistic interactions with other agents, DU is a promising fluoroquinolone for use against enterococci, although prior development of resistance to currently available fluoroquinolones diminishes some of its effect.Publication Metadata only Acute purulent exacerbation of chronic obstructive pulmonary disease and Chlamydia pneumoniae infection(AMER THORACIC SOC, 1999) KARAKURT, SAİT; Mogulkoc, N; Karakurt, S; Isalska, B; Bayindir, U; Celikel, T; Korten, V; Colpan, NIn order to investigate the role of bacteria, including Mycoplasma pneumoniae and especially Chlamydia pneumoniae in acute purulent exacerbations of chronic obstructive pulmonary disease (COPD), we examined sputum specimens and acute and convalescent sera taken 26 d apart from 49 outpatients experiencing an acute purulent exacerbation of COPD. The sera were tested for antibodies to C, pneumoniae with the microimmunofluorescence test, and for antibodies to M. pneumoniae with the indirect fluorescence antibody test. Routine microbiologic culture of sputum yielded potentially pathogenic microorganisms in 12 of the 49 patients (24%). Three patients (6%) showed serologic evidence of recent M. pneumoniae infection. Seven patients showed high IgG titers of greater than or equal to 1:1,024 to C. pneumoniae, and an additional four had a fourfold increase in IgG titer, suggesting reinfection with C. pneumoniae. Sputum from two of these 11 patients also grew Streptococcus pneumoniae, and one grew Moraxello cotarrhalis. Patients with and without serologic evidence of current C. pneumoniae infection showed no significant differences in clinical features or pulmonary function. The high incidence of infection with C, pneumoniae (the sole causal agent in 16% of cases, and the causal agent with other agents in 6%) provides insight into the importance of this organism among agents leading to exacerbations of COPD in Turkey.